amavisd-new consists of a daemon 'amavisd', and (in some setups) a helper
program, which is only needed with certain mail transport agents (MTA).
For Postfix, Exim-V4, and dual-sendmail setups no helper program is needed
for interfacing MTA with amavisd daemon .
Obtaining the software:
=======================
Fetch the tarball and unpack it:
curl -O http://www.ijs.si/software/amavisd/amavisd-new-<version>.tar.gz
gzip -d -c amavisd-new-<version>.tar.gz | tar xvf -
cd amavisd-new-<version>
The most important files thus obtained are amavisd and amavisd.conf.
Start reading with AAAREADME.first, then RELEASE_NOTES if upgrading,
and INSTALL and README_FILES/<your-MTA> for new installations.
Check also the on-line documentation at:
http://www.ijs.si/software/amavisd/
and http://www.ijs.si/software/amavisd/amavisd-new-docs.html
Prerequisites:
==============
file(1) utility is required, the most recent version is heartly recommended
(current version is 4.24 at the time of a release). There are a number of
security and robustness problems with older versions.
Archive::Zip (Archive-Zip-x.xx) (1.14 or later, currently 1.30)
Compress::Zlib (Compress-Zlib-x.xx) (1.35 or later, currently 2.060)
Compress::Raw::Zlib (Compress-Raw-Zlib) (2.017 or later)
MIME::Base64 (MIME-Base64-x.xx)
MIME::Parser (MIME-Tools-x.xxxx) (currently 5.504)
Mail::Internet (MailTools-1.58 or later have workarounds for Perl 5.8.0 bugs)
Net::Server (Net-Server-x.xx) (version 2.0 adds support for IPv6)
Digest::MD5 (Digest-MD5-x.xx) (2.22 or later)
Time::HiRes (Time-HiRes-x.xx) (1.49 or later)
Unix::Syslog (Unix-Syslog-x.xxx)
Mail::DKIM (Mail-DKIM-0.31 or later, currently 0.40)
The following external programs are used for decoding/dearchiving
if they are available:
compress, gzip, bzip2, nomarch (or arc), lha, arj (or unarj), rar (or unrar),
unzoo (or zoo), pax, cpio, lzop, freeze (or unfreeze or melt), ripole,
tnef, cabextract.
Self-extracting archives (executables) can be of types zip, rar, lha or arj,
and are only recognized when the corresponding dearchiver is available.
optional Perl modules:
Mail::SpamAssassin for doing spam scanning (latest version)
DBI with appropriate DBD::* if using SQL lookups or SQL logging/quarantining
Net::LDAP if using LDAP lookups
ZeroMQ or ZMQ::LibZMQ[2,3] Perl module interface to libzmq
optional, but usually desired:
virus scanners external programs for doing virus scanning, like ClamAV
Some external programs may already be provided with the system, but it is
worth checking that their version is recent. The following lists the programs
and their distribution sites (not necessarily the only or the official).
The most crucial programs are marked with an asterisk:
* file: ftp://ftp.astron.com/pub/file/
compress: ftp://ftp.warwick.ac.uk/pub/compression/
* gzip: http://www.gzip.org/
bzip2: http://www.bzip.org/
nomarch: http://rus.members.beeb.net/nomarch.html
arc: ftp://ftp.kiarchive.ru/pub/unix/arcers/
lha: http://www2m.biglobe.ne.jp/~dolphin/lha/lha.htm
7z: http://p7zip.sourceforge.net/, http://www.7-zip.org/
unarj: ftp://ftp.kiarchive.ru/pub/unix/arcers/
arj: http://testcase.newmail.ru/files/ (arj is preferable to unarj)
rar, unrar: http://www.rarsoft.com/, http://www.rarsoft.com/rar_add.htm,
ftp://ftp.kiarchive.ru/pub/unix/arcers/ (rar preferred to unrar)
unzoo: http://critical.ch/distfiles/
zoo: ftp://ftp.kiarchive.ru/pub/unix/arcers/ (zoo preferred to unzoo)
lzop: http://www.lzop.org/download/
freeze: ftp://ftp.warwick.ac.uk/pub/compression/
ripOLE: http://www.pldaniels.com/ripole/
tnef: http://tnef.sourceforge.net/
* pax: http://www.gnu.org/software/paxutils/
or: http://heirloom.sourceforge.net/
cpio: http://www.gnu.org/software/cpio/
or: http://heirloom.sourceforge.net/
cabextract: http://www.kyz.uklinux.net/cabextract.php
* ClamAV: http://clamav.elektrapro.com/ (open source virus scanner)
dspam: http://www.nuclearelephant.com/projects/dspam/
bdb: http://www.sleepycat.com/ (Berkeley db libr. used via BerkeleyDB)
p0f: http://lcamtuf.coredump.cx/p0f.shtml
Optional third-party utilities:
MailZu: http://www.mailzu.net/ (quarantine management web UI)
amavisd-milter: http://sourceforge.net/projects/amavisd-milter/
(alternative sendmail milter helper program supporting the
new AM.PDP protocol)
See also: http://www.ijs.si/software/amavisd/#contrib
Installing the daemon:
======================
- Perl version 5.8.2 or later is recommended. While 5.6.1 may theoretically
still be the lowest usable version, a bunch of problems were resolved in
later Perl versions which were reported to show in certain environments.
Some examples: taint bugs, socket descriptors not closed on exec,
Net::Server looping waiting for a socket connect, problems with handling
of UTF8/Unicode in Perl;
- create (or choose) a Unix group dedicated to run amavisd daemon and
possibly virus scanners. This should NOT be one of user or system groups
and should NOT be shared with other applications such as mail or www
(except possibly virus scanners). It is customary to name the group
'amavis' (or perhaps 'vscan' or 'sweep');
(edit /etc/group, or use system-specific tools, such as vigr)
- create (or choose) a Unix account (username and its UID) dedicated to run
amavisd daemon and possibly virus scanners. This should NOT be one of user
or system accounts and should NOT be shared with other applications such
as mail or www (except possibly virus scanners). Most certainly do NOT use
"root", and do NOT use "nobody" nor an account used by mailer, such as
"postfix", "mail", "smmsp" or "mailnull"). It is customary to name the
user "amavis" or "vscan";
Choose a home directory (e.g. /var/amavis or /var/lib/amavis) for this user.
(use vipw, or system-specific tools to add a user)
Create its home directory, unless account creation procedure already did it:
mkdir /var/amavis
Create the following subdirectories:
mkdir /var/amavis/tmp /var/amavis/var /var/amavis/db /var/amavis/home
Check or set the ownership and protection of the directories to be readable
and writable by the chosen UID, and not writable by other non-privileged
users;
chown -R amavis:amavis /var/amavis
chmod -R 750 /var/amavis
- unpack the amavisd-new source distribution (see 'Obtaining the software'
above) wherever desired (/usr/local/src or elsewhere), and cd to that
directory;
- copy file amavisd to wherever you want it to reside,
such as /usr/local/sbin, and make sure its protection setting allows it
to be executed and read, but not overwritten by non-privileged users.
This is a Perl source, so it is readable by any text viewer if needed.
cp amavisd /usr/local/sbin/
chown root /usr/local/sbin/amavisd
chmod 755 /usr/local/sbin/amavisd
- copy file amavisd.conf to wherever you want it to reside such as /etc, and
make sure it is not writable by non-privileged users, not even by amavis;
cp amavisd.conf /etc/
chown root:amavis /etc/amavisd.conf
chmod 640 /etc/amavisd.conf
(if the file contains sensitive information like a password for accessing
a SQL database, it should not be world-readable)
Some sites prefer location /etc/amavis/ or /usr/local/etc/. If using
a non-default location, one may use a command line option -c when
starting the daemon to specify a non-default configuration file,
or provide a soft link at the default location. Multiple -c options
are permitted and enable splitting the config file into sections such
as site-specific and general sections;
- create a directory (e.g. /var/virusmails) to be used by amavisd-new
as a quarantine area (if quarantining to files is desired).
Set ownership and protection of the directory to be readable and
writable by the chosen UID, and not writable by other non-privileged
users;
mkdir /var/virusmails
chown amavis:amavis /var/virusmails
chmod 750 /var/virusmails
- edit file /etc/amavisd.conf and adjust variables $daemon_group
and $daemon_user to match the chosen group and user name,
adjust variables $MYHOME, $TEMPBASE, $db_home and $QUARANTINEDIR
to match the directories just created, then check/adjust other variables,
for example:
$MYHOME = '/var/amavis';
$TEMPBASE = "$MYHOME/tmp";
$db_home = "$MYHOME/db";
Optionally, if $MYHOME is preferred uncluttered and for extra security
owned by root (not modifyable by user amavis):
$MYHOME = '/var/amavis';
$helpers_home = "$MYHOME/home";
$pid_file = "$helpers_home/amavisd.pid";
$lock_file = "$helpers_home/amavisd.lock";
in which case the ownership of /var/amavisd should be changed to root
and ownership of /var/amavis/home must be amavis:
chown root /var/amavis
chown -R amavis:amavis /var/amavis/home
chmod 750 /var/amavis /var/amavis/home
If $TEMPBASE resides on a dedicated file system, it may be prudent to
specify mount options: noexec,nosuid,nodev.
- install virus scanners (if they are to be used), and Perl module
Mail::SpamAssassin (if desired), and adjust variables in /etc/amavisd.conf.
There are several other Perl modules needed by amavisd daemon
(see 'Prerequisites') - if they are not yet installed, a list
of missing modules will be logged when amavisd is started;
- some virus scanners run as daemons or change UID when checking files.
It is easiest to run such virus scanners under the same UID/GID (or at least
within the same group) as amavisd, to avoid file permission problems
when virus scanner reads files prepared for checking by amavisd daemon.
Some virus scanners may require write permission to the $TEMPBASE directory
to be able to create auxiliary files there.
If a different UID is preferred for an AV scanner, a solution for ClamAV
is to add user clamav to the amavis group (e.g.: vscan:*:110:clamav
in a file /etc/group), and then add: AllowSupplementaryGroups yes
to clamd.conf.
- start the program 'amavisd', either as root (possibly with option
-u user), or with su(1) as the user chosen above. It should
start up, and (if root) change its GID/UID to the setting provided.
It is wise to start it up for the first time with a 'debug' option:
/usr/local/sbin/amavisd -u vscan debug
or:
/usr/local/sbin/amavisd debug
When checking SpamAssassin operations, the following can be useful:
/usr/local/sbin/amavisd debug-sa
- later when everything has been tested and works, a shell script
amavisd_init.sh or similar may be made to run at system startup/shutdown
time;
- depending on the mailer used, read the appropriate README.* file
and follow instructions there. With some mailers (Postfix, Exim V4
or a dual-MTA setup with any SMTP-capable mailers, including sendmail)
no helper program is needed.
With some other mailers (sendmail milter, or historical sendmail invoking
content filter via local delivery agent) one of the supplied helper
programs is needed: amavisd-milter.c, or amavis.c respectively. These are
available from the helper-progs subdirectory. The helper-progs/config.h.in
may need to be adjusted to match the system and amavisd configuration
settings. See also alternative sendmail milter supporting the new AM.PDP
protocol at http://sourceforge.net/projects/amavisd-milter/ .
NOTE:
Check amavisd-new web page at http://www.ijs.si/software/amavisd/
if there are any patches needed for external components, such as
Net::Server module or Razor agents.
Testing the daemon:
===================
Initial checkout is described in MTA-specific README.* file,
please follow instructions there.
The subdirectory test-messages contains a couple of sample mail messages,
and brief instructions for testing are in file README there.